Ultrastructure of cells - planning 1.2

Planning sheet for ultrastructure of cells

Desired Results

Understanding(s)

The simple structure of Prokaryote cells
Prokaryote cell structure & function
The compartmentalised structure of Eukaryotic cells.
Eukaryotic cell ultrastructure
The difference in resolution between electron microscopes and light microscopes.

Essential Question(s)

How does the presence of membrane bound organelles benefit eukaryotic cells?
How many different organelles are there?
Do prokaryotes and eukaryotes share any common organelles?
What do we mean by resolution, or resolving power of microscopes?

ToK / NOS / IM

Developments in equipment help new discoveries in science.
Is there any difference between observations made using sense perception directly and those using technology, e.g. microscopes?
Modern ICT has improved international collaboration and communication.

Skills students will have

Application: ability to explain how the composition of organelles will be different in cells with different functions, e.g. exocrine gland cells and palisade mesophyll cells.
Application: explain how the structure of prokaryotes allows them to divide by binary fission.
Skill: Drawing prokaryotic cells (cell wall, plasma membrane, cytoplasm, pili, flagella, 70s ribosomes and nucleoid.) and eukaryotic cells (free 80s ribosomes, rough endoplasmic reticulum (rER), lysosome, Golgi apparatus, mitochondrion and nucleus) based on electron micrographs.
Yoghurt and milk bacteria experiment
or
Mobile phone bacteria experiment
Skill: Identification of organelles and deduction of the function of specialized cells.
Cell types detective activity

Assessment Evidence

Completion of worksheets included in the following tasks will give evidence of understanding.

There are quick tests the IB style questions in the lessons on eukaryote cells, prokaryote cells and the cell detective activity. The students will show their understanding of the key concepts about both types of cells by answering these questions.

The activities looking at prokaryotes in yoghurt, growing prokaryotes on mobile phones and the cell detective activity ask students to apply their knowledge in new situation and will help to identify students who have difficulty making comparisons, or distinguishing between cell organelles.

The experimental work on prokaryotes gives students an opportunity to process data and write a simple conclusion and evaluation.

There is also a 'webquest' style investigation to spot errors in images of cells found on the web.
Students who have a good grasp of the structure of cells will enjoy this activity.

Learning Activities

	Eukaryote Cells and their Organelles Time: 1h This activity contains range of resources to teach about the structure of eukaryotic cells. An introduction to cell ultrastructure including a student activity sheet with examiner's hints is followed by a short screencast explaining how to draw a eukaryotic cell diagram simply so that it doesn't take too long during the exam. Flashcards help students' learn the organelle labels, followed by some questions including a data based IB style question.
	Prokaryote Cell Structure & Function Time: 1h Students learn how to draw and label a diagram of the ultrastructure of Escherichia coli (E. coli) as an example of a prokaryote. Using a webcast and revision flashcards the teacher has more freedom to assist students individually..
	Yoghurt and milk bacteria experiment Time: 1h This lab is a safe way to demonstrate the structure of prokaryotes. The comparison of slides of milk and yoghurt illustrates the variety of bacteria and their small size and it is an opportunity to extend microscopy skills to Gram staining. This could be used as a 'mini IA' to introduce students to an aspects of the Individual assessment, such as sample size or hypothesis testing.
	Mobile Phone Bacteria Experiment? Time: 1h Students takes samples from their mobiles phones and grow prokaryote colonies on agar plates. (Hygiene note: The IB now advises not to sample bacteria from classroom surfaces for the IA - so this lab has been replaced by the Yoghurt and milk bacteria experiment. It has been left here for the moment as some school systems encourage microorganism experiments using aseptic techniques) This activity is combined with a 'webquest' to perfect prokaryote diagrams.
	Cell Detective Activity Time: 1h A Problem Based Learning activity - to challenge students to compare different types of cells and to outline differences between plant and animal eukaryote cells and prokaryote cells.